1. Field of the Invention
The present invention relates to heat supply systems. More particularly, this invention relates to a heat supply system for use in a building having a number of separate and distinct compartments, such as an apartment house, a general office building, and a plant.
2. Prior Art
In recent years, unified heat supply systems have been employed for supplying heat in buildings such as described above by circulating a suitable fluid heat carrying medium, such as water, heated by a heat exchanger, to load members such as boilers, heating equipment, and driers. FIG. 10 in the drawings is a piping diagram showing a conventional type of such a supply system in a building 50, which is a 4-storied collective housing one. As shown in FIG. 10, a feed main pipe 52 and a return main pipe 53, each provided in the lateral direction, are connected to a heat exchanger 51 provided on the ground floor. A plurality of pipe shafts 60 extend through each of the compartments adjoining each other in the vertical direction. Each of the pipe shafts 60 accommodates therein a feed branch pipe 54 and a return branch pipe 55, with the edge sections connected to the feed main pipe 52 and the return main pipe 53, respectively. A plurality of load pipes 56, corresponding to compartments adjoining each other in the vertical direction are connected to each other between a feed branch pipe 54 and a return branch pipe 55, while load members, such as boiler 57, are provided in each of load pipes 56.
Each of the feed branch pipes 54 and the other edge section of each return branch pipe 55 are connected to each other with a by-pass pipe 59 having a flow control valve 58. Because of this configuration, the water heated by the heat exchanger 51 flows through the feed main pipe 52, feed branch pipe 54, by-pass pipe 59, return branch pipe 55, and return pipe 53 and returns to the heat exchanger 51, thus circulation being maintained, even without using all of the plurality of load members 57 in a combination of the feed branch pipe 54 and the return branch pipe 55. Therefore, the hot water is supplied immediately when a demand from any load member 57 is started.
The hot water supply system as described, however, has the defects as described below. Namely a flow of the hot water between the feed branch pipe 54 and the return branch pipe 55 via each of the load pipes 56 is caused by the differential pressure effect (header effect) generated between the two pipes 54, 55. To evenly distribute the hot water to each of the load pipes 56 by making use of the differential pressure effect, the heat emission loss must be taken into account.
This is typically done by using larger pipe diameters of both the feed branch pipe 54 and return branch pipe 55 at their connecting sections with the feed main pipe 52 and return main pipe 53 and also using gradually smaller pipe diameters toward the edge sections.
For the reasons described above, it is necessary to provide a number of pipes having different diameters, and the initial cost is disadvantageously high. Further the heat emission loss remains large because sections having large pipe diameters are included in the piping system. Further in the conventional heat supply system, the feed branch pipe 54 and return branch pipe 55 are generally accommodated in a pipe shaft that extends through the building frame, making exchange of the piping materials with new ones for repairing or for other purposes practically impossible.
The present invention was made in the light of the technological circumstances as described above. An object of this invention is to provide a heat supply system for use in a multi-story building having a number of separate and distinct compartments in which pipes having the same diameter can be used for both the feed branch pipes and return branch pipes to and from each compartment to reduce the initial cost and the pipes can be small diameter to suppress the heat emission loss.
It is another object of the invention to provide a heat supply system in which piping materials can easily be exchanged and interchanged, thus enabling quick response to needs for repairing or improvement.
The present invention employs the following means to achieve the objectives as described above. Namely this invention provides a heat supply system comprising a heat exchanger (1); a feed main pipe (2) connected to said heat exchanger for supplying a heat medium heated by said heat exchanger to a load member (7); a return main pipe (3) connected to said heat exchanger for returning the heat medium thermally consumed by said load member to said heat exchanger; a feed branch pipe (4) connected to said feed main pipe; a first return branch pipe (5) for distributing the heat medium to an edge section in the downstream side of said feed branch pipe; a plurality of load pipes (8) connected in parallel to each other between said feed branch pipe and said first return branch pipe each having said load member provided therein; and a second return branch pipe (6) connected between an edge section in the downstream side of said first return branch pipe and said return main pipe, wherein said feed branch pipe, said first return branch pipe, said load pipe, and said second return branch pipe are provided in plurality respectively.
With the present invention, a heat medium heated by the heat exchanger is sent through the feed main pipe, feed branch pipe and load pipe to a load member. The heat medium thermally consumed by the load member returns through the first return branch pipe, second return branch pipe, and return main pipe to the heat exchanger, and is heated again. With the piping system as described above, it is possible to make the path length from the feed main pipe to the return main pipe for any load member be the same, and the head loss in each path is thus equalized. Therefore even when pipes having the same small diameter are used for the feed branch pipe, first return branch pipe, and second return branch pipe, it is possible to evenly distribute the heat medium to each load member.
Further with the present invention, a by-pass pipe (10) having a flow control member (9) is connected to a section between the feed branch pipe and an edge section in the downstream side of the first return branch pipe. Further the feed branch pipe and the first and second return branch pipes are bundled. The pipes may be bundled in parallel to each other, or may be bundled in the twisted state. The feed branch pipe and the first and second return pipes are provided in the lateral direction outside each floor of a building frame consisting of multiple floors. A reversed U-shaped combustion gas pathway is formed in the heat exchanger